Neurobiology: Neurotransmitters, Receptors and Autonomic Nervous System - Test 3
A membrane protein that transports neurotransmitters, or their precursors, across membranes to concentrate them in either presynaptic cytosol or synaptic vesicles.
A protein that transports ions across a membrane at the expense of metabolic energy.
A change in membrane potential, taking it from the value at rest (e.g., 65 mV) to a less negative value (e.g., 0 mV). Rising curve (more positive)
The last part of an action potential, also called
undershoot. The part of an action potential when the membrane potential is more negative than at rest. Tends to reduce excitability.
A membrane-spanning protein that forms a pore that allows the free passage of ions from one side of the membrane to the other.
Patch clamp recording
A method that enables an investigator to hold constant the membrane potential of a patch of
membrane while current through a small number of
membrane channels is measured.
Resting membrane potential (Vm)
The difference in electrical charge across the membrane, or membrane voltage, maintained by a cell when it is not generating action potentials; also called resting potential. Neurons have a resting membrane potential of about 65 mV.
A toxin that blocks Na permeation through voltage-gated sodium channels, thereby blocking action potentials.
A brief fluctuation in membrane potential caused by the rapid opening and closing of voltage-gated ion channels; also known as spike, nerve impulse, or discharge. ___s sweep like a wave along axons to transfer information from one place to another in the nervous system.
Inhibitory postsynaptic potential (IPSP)
A change in the postsynaptic membrane potential by the action of a synaptically released neurotransmitter, making the postsynaptic neuron less likely to fire action potentials. Caused by synaptic activation of glycine-gated or GABA-gated ion chanels. (Cl- in)
Excitatory postsynaptic potential (EPSP)
Depolarization of the postsynaptic membrane potential by the action of a synaptically released neurotransmitter. Caused by synaptic activation of ACh-gated and glutamate-gated ion channels. (Na+ in)
A transient current that flows across the cell membrane in response to voltage change, thereby recharging the membrane capacitance to the new membrane potential. Applied experimentally to restore/change the resting membrane potential.
Absolute refractory period
The period of time, measured from the onset of an action potential, during which another action potential cannot be triggered, until the membrane potential goes sufficiently negative to reactivate the channels.
A simple form of synaptic integration whereby excitatory postsynaptic potentials generated at more than one synapse on the same cell combine to produce a larger postsynaptic depolarization.
A level of depolarization sufficient to trigger
an action potential.
An increase in evoked release of transmitter from nerve terminals, due to previous synaptic activity; can last for several hundred ms.
An decrease in evoked release of transmitter from nerve terminals, due to previous synaptic activity; can last for several hundred ms.
Long-term potentiation (LTP)
A long-lasting enhancement of the effectiveness of synaptic transmission that follows certain types of conditioning stimulation (lasts hours).
Long-term depression (LDP)
A long-lasting decrease in the effectiveness of synaptic transmission that follows certain types of conditioning stimulation (lasts hours), such as repeated inhibitory or hyperpolarizing stimulus.
Reduction of the response of a receptor to a ligand after prolonged or repeated exposure.
A mathematical relationship used to calculate an ionic equilibrium potential.
Eion = 58/z log [out]/[in]
Complementary peptide protein embedded in membrane of vesicle that allows vesicle to dock close to presynaptic membrane.
Complementary peptide protein embedded in membrane of target neuron that allows vesicle to dock close to presynaptic membrane.
The process whereby material is released from an intracellular vesicle into the extracellular space by fusion of the vesicle membrane with the cell membrane.
The region separating the presynaptic and postsynaptic membranes of neurons.
A membrane-enclosed structure, about 50 nm in diameter, containing neurotransmitter and found at a site of synaptic contact.
Secretion of multimolecular packets (quanta) of neurotransmitter by the presynaptic nerve terminal.
Clathrin coated pit
Vesicles associated with the cystolic protein. Form domains of the plasma membrane termed ___, which concentrate large extracellular molecules that have different receptors responsible for the receptor-mediated endocytosis of ligands.
The process by which a bit of the cell membrane is pinched off, internalized, and converted to an intracellular vesicle (endosome).
Reabsorption of a neurotransmitter by a neurotransmitter transporter of a pre-synaptic neuron after it has performed its function of transmitting a neural impulse. Allows for the recycling of neurotransmitters and regulates the level of neurotransmitter present in the synapse and controls how long a signal resulting from neurotransmitter release lasts.
Autonomic nervous system
A system of central and peripheral nerves that innervates the internal organs, cardiovascular system, and glands; also called visceral PNS. The ___ consists of sympathetic, parasympathetic, and enteric divisions.
A neuron of the sympathetic and parasympathetic divisions of the autonomic nervous system; its cell body lies in the CNS (spinal cord or brain stem), and its axons extend peripherally to synapse on postganglionic neurons in the autonomic ganglia.
A peripheral neuron of the sympathetic and parasympathetic divisions of the autonomic nervous system; its cell body lies in autonomic ganglia, and its axons terminate on peripheral organs and tissues.
A division of the autonomic nervous system that in fight-or-flight situations activates physiological responses, including increased heart rate, respiration, blood pressure, and energy mobilization and decreased digestive and reproductive functions; its peripheral axons emerge from the thoracic and lumbar spinal cord.
Pre G mACh -> Norepinephrine Post G neuron
A division of the autonomic nervous system that maintains heart rate and respiratory, metabolic, and digestive functions under normal conditions; its peripheral axons emerge from the brain stem and sacral spinal cord.
Local ganglia near target tissue. Pre nACh -> mACh Post G neuron
A division of the autonomic nervous system that innervates the digestive organs; consists of the myenteric (smooth muscle) and submucous (connective tissue) plexuses.
glutamic acid decarboxylase
(1) GABA alphar-oxoglutarate transminase and (2) succinic semialdehyde dehydrogenase
(1) tyrosine hydroxylase and (2) aromatic L-amino acid decarboxylase
MAO (then ADH or AR and COMT) or (1) COMT and (2) MAO (then AR/ADH)
MAO or via COMT
(1) tryptophan-5-monooxygenase (2) aromatic L-amino acid decarboxylase
(1) monoamine oxidase (2) aldehyde dehydrogenase or aldehyde reductase
(1) diamine oxidase and (2) aldehyde dehydrogenase
OR (1) histamine methyltransferase (2) MAO and (3) aldehyde dehydrogenase
Aldehyde -> Alcohol
Aldehyde -> acid
COMT (catechol O-methyltransferase)
Monoamine oxidase (MAO)
enzyme in many neurotransmitter degradation processes
Hypothalamic neuropeptides that regulate sleep and feeding; aka hypocretins.
Nitric oxide; a gaseous molecule proposed for intercellular communication. May be a retrograde messenger that is smaller and membrane permeable. Breaks down quickly.
Transmitter released at many inhibitory synapses in the spinal cord and brainstem.
Small neuropeptides comprising five amino acids that act on opioid receptors.
Term for movement of proteins, intracellular particles and organelles along axons.
Voltage activated channel
A channel that is activated or inactivated by changes in membrane potential.
Ligand gated ion channel
A channel that is activated by binding an ion or molecule to an external or internal receptor region of the channel.
An ion channel that is opened by a neurotransmitter or other chemical ligand (i.e. nicotinic ACh receptor)
A neurotransmitter receptor that interacts with another membrane protein such as G protein to produce its effect on the neuron; can trigger widespread metabolic effects.
GluN1 - four subunits, 2 Glu binding, 2 Gly binding
Can also bind aspartate and D-serine respectively
Transmitter and voltage activated; permeable to Ca++; slower turnover
Metabotropic Glutamate receptors
Multispan G protein-coupled receptors, 7 TM domains; play a role in late LTP using G protein signaling
GluN2 - four subunits, 2 Glu binding, 2 Gly binding
Translocated from latent pool to synapse
Permeable to Na+ and K+
Phosphorylation by CaMKII during LTP changes their conformation, increases their conductance to Ca++
1) AMPA, 2) NMDA and 3) Kainate
Ionotropic- AChR, ligand-gated ion channels-pentameric-10 human alpha subunits, 4 beta subunits, plus 1 each delta, epsilon and gamma.-Cys loop superfamily- fast acting
Metabotropic AChR G-protein coupled-induce signaling changes that release intracellular Ca++, slower in action
Muscarinic and Nicotinic
H1, H2, H3. Work as G protein coupled receptors. Broad projections from tuberomammillary nucleus underlie a role in sleep/wake cycles and motor control.
5HTR1-5 - respond to raphe nuclei projections, Mediate mood, behavior, wakefulness, attention, (aggression in some species)
Mostly metabotrpic (GPCR's), few ionotropic
Multispan transmembrane receptors
D1, D5 - activate adenylate cyclase
D2-D4 - inhibit adenylate cyclase
alpha & beta subunits
Locus coerulus projections and auto innervation to control firing rate (negative feedback loop)
Activation of primary somatosensory cortex and central sulcus, other sulci, primarty motor cortex, medial premotor cortex, prefrontal cortex, posterior parietal cortex, etc
Damage results in agnosia (inability to recognize objects) or neglect syndrome (ignored body part)
Ventral pathway in object recognition and dorsal pathway for motion perception.
Activation of primary visual cortex (V1), V2, V4, temporal cortex, fusiform face area (ventral), central sulcus, medial temporal and medial superior temporal areas (dorsal).
Vesicle protein that is triggered by Ca++ to induce vesicle fusion, inducing interaction between tSNARE and vSNARE proteins for vesicular docking.
The bility of the connection, or synapse, between two neurons to change in strength in response to either use or disuse of transmission over synaptic pathways.